干旱区生态环境知识资源中心

The problems considered concern the Eocene-early Miocene evolution of vegetation cover and large mammals in extratropical Asia. As a rule, the evolutionary stages revealed coincided with certain moments of ecological rearrangement related to geologic and paleogeographic events. The narrow-leaved xeromorphic flora of the Bartonian marked the closure time of an open marine strait, which connected the Tethys and Arctic basins. This was a time of intense radiation of phytophagous mammals and coeval development of endemism of Asiatic ungulates. The mesoxerophilic flora of evergreen and deciduous plants, some of which later became basic elements of the Turgai flora, existed at the prosperity time of brontotherioid and tapiroid faunas. Giant Indricotheriinae were widespread at the mid-Oligocene time, when the climate in expanded open landscapes became more arid. Formation of deciduous flora of the Turgai ecotype was completed under conditions of the humid, moderately warm climate of the late Oligocene. Remains of large mammals of this time are very scarce.